CT Dose Index (CTDI)

CTDIw: Describes the dose product in a single rotation across the z axis 

CTDIvol: CTDIw x pitch

Altered by kV, mA, rotation time, beam collimation and pitch

Units of mGy

Dose Length Product (DLP)

A dose product based on the CTDI and the length of the scan. 

DLP: CTDIvol x z-axis length

Altered by kV, mA, rotation time, beam collimation, pitch and scan length

Units of mGy/cm

Effective dose

Takes into account the patients size and tissue weighting factors.

Calculated by physicists 

Units of mSv                                                        (1)